Adjustable reinforcing element for a motor vehicle body for protection in case of a rear impact or side impact

ABSTRACT

A reinforcing element (10) for a motor vehicle body (1) comprising protection means (30, 31, 40, 41, 42) for protection against an impact at the rear of the vehicle, characterised in that it comprises at least two tubes (20, 22) to be positioned, generally, in the length direction of the vehicle, and a rigid contact surface (30, 31, 70) turned towards the rear, the rigid contact surface (30, 31, 70) and the two tubes (20, 22) being arranged with respect to each other in order to allow the vehicle to move in case of an impact at the rear.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is the US National Stage under 35 USC § 371 ofInternational Application No. PCT/FR2017/051838 filed Jul. 6, 2017,which claims priority to French App. No 1657487 filed Aug. 2, 2016; bothof said applications being incorporated herein by references.

BACKGROUND

The invention is within the field of motor vehicle bodies, in particularelectric or hybrid motor vehicles.

These vehicles must be protected in case of impact, in particular rearimpact or side impact.

There is a particular interest in protection from so-called “70% offset”rear impacts, for example at a speed of 80 km/h or other high speed.This is a high-energy impact. There is also an impact in the class ofimpacts called “side pole impact (centered on the rear)”. This is a veryintrusive impact. These impact categories are non-limiting for thepurposes of the present disclosure, but are mentioned as anillustration.

It is desirable for vehicles to be well protected in case of impact, butnevertheless to retain a lighter silhouette. There is therefore a wishto develop hybrid or electric propulsion vehicles using the lines asunits with compact rears, with a larger wheelbase and a smaller rearoverhang, and/or copying existing rear axle (rear suspension systems).There is also an interest in using cost-effective rear axle systems(rear axle with deformable crossmember, in particular).

If a rear axle with deformable crossmember is reused, for which onewishes to copy the body, there is cause to add, for an electric vehicle,two battery modules, in front of and behind the axle, below the body ofthe vehicle, and for a hybrid vehicle, a battery module behind the axleand a fuel tank in front of the axle. These elements, placed on eitherside of the vehicle, must be protected in case of rear impact or sideimpact.

To satisfy these new constraints, the state of the art consists ofreinforcing the existing designs in terms of the strength of the bodyunderstructure. For example, it is possible to insert a centralauxiliary longitudinal member for rear impacts, or a continuous chassisframe rail reinforcement and an inner reinforcement for side impacts:this is reflected by an increase in the mass of the structure, but alsothe challenge to the rear unit, which involves costly investments for anew industrial facility. This also involves a higher mass.

WO201286297 discloses a body structure with controlled buckling of abattery support frame. However, the support frame is not configured tostiffen the structure and allow the vehicle to be set in motion in caseof rear impact.

An effort has therefore been made to design a system that satisfies theprevious constraints without having the mentioned defects.

Proposed in this context is a reinforcing element for a motor vehiclebody, the reinforcing element comprising protection means for protectingagainst an impact at the rear of the vehicle, characterized in that itcomprises at least two tubes to be positioned, generally, in the lengthdirection of the vehicle and to be fastened to the body as well as arigid contact surface comprising impactors. The rigid contact surface isarranged opposite the two tubes to allow the vehicle to be set in motionin case of impact at the rear, the reinforcing element additionallycomprising energy absorbing means protruding opposite the rigid contactsurface and to be positioned toward the rear of the vehicle, such thatthe impactors only come into play for setting in motion if the energyabsorbing means have been stressed and overcome by such an impact at therear.

The invention may also comprise the following optional and advantageousfeatures:

-   -   a protection structure for a battery or a fuel tank that may be        present below the body of the vehicle;    -   for each side of the vehicle, a rigid contact surface oriented        toward the side to absorb the energy from any side impact;    -   a means for fastening to the adjustable body to adapt to the        wheelbase of the vehicle;    -   three tubes to be positioned generally in the direction of the        length of the vehicle, to stiffen the reinforcing element and        transmit the energy in the forward direction; these three tubes        to be positioned generally in the direction of the length of the        vehicle for example comprise two tubes to be placed between a        rear axle and the body, and a third tube, midway between said        two tubes, being such that the rear axle is to be placed between        the body and said third tube;    -   on at least one of the tubes, a means for fastening to the body        bottom, opposite the rigid contact surface.

The reinforcing element can be made up of steel or aluminum tubes.

Also proposed is a motor vehicle with a rear axle having a deformablecrossmember, characterized in that it also comprises a reinforcingelement as described above.

This motor vehicle may comprise a first battery below the body andbehind the rear axle and respectively a second battery or a fuel tankbelow the body and in front of the rear axle, the first battery andrespectively the second battery or the fuel tank being protected by thereinforcing element.

DESCRIPTION OF THE FIGURES

The invention will be better understood, and other aims, features,details and advantages thereof will appear more clearly in the followingexplanatory description done in reference to the appended drawings,provided solely as an example illustrating embodiments of the inventionand in which:

FIG. 1 shows a first version of a reinforcing element placed on anelectric vehicle;

FIG. 2 shows the same reinforcing element, but placed on a hybridvehicle;

FIG. 3 shows a second version of the reinforcing element, on a hybridvehicle;

FIG. 4 shows a third version of the reinforcing element on a hybridvehicle equipped with two batteries.

DETAILED DESCRIPTION

FIG. 1 shows the rear part of the body 1 of a motor vehicle, seen frombelow. One can in particular see the batteries 2 and 3 placed below theinner surface of the body, across the vehicle, on either side of therear axle 5. This is a rear axle with a deformable crossmember, whichhas the advantage of being cost-effective.

The vehicle is equipped with a reinforcing element 10 in the form of anarrangement of tubes welded to one another. The reinforcing element, inparticular, comprises longitudinal tubes 20, 21 and 22, on the left ofthe vehicle, in the middle of the vehicle and on the right of thevehicle. The tube 21, midway between the tubes 20 and 22, is placed suchthat the batteries 2 and 3 and the axle 5 are placed between the body 1and the tube 21. The tubes 20 and 22 are in turn placed so as to beplaced between the axle 5 and the body 1.

Toward the rear, the reinforcing element 10 comprises two side impactors30 and 31 making up a rigid contact surface, having a barrier function,for setting the vehicle in motion in case of a rear impact. These twostructures 30 and 31 are in the same position on each of the two sidesof the body. They are connected by a tube of the structure, which willbe mentioned later.

Also seen at the rear, the reinforcing element 10 comprises threeabsorbers 40, 41 and 42 having an energy absorption role in case of rearimpact. They are able to deform to perform a buffer role, and to preventthe rest of the vehicle from receiving too much energy. They are mountedon sliding tubes so that their length is adapted to the rear overhang ofthe vehicle on which the reinforcing element is mounted. They protruderelative to the rigid surface defined by the impactors 30 and 31 and thetube connecting them. They are to be positioned toward the rear of thevehicle.

The impactors 30 and 31 only come into play if the absorbers 40, 41 and42 have been stressed and overcome, by a high-energy impact.

The reinforcing element 10 includes the fastening zones 50 and 51,respectively on the left and right of the vehicle. They make itpossible, for example using a screw-nut system, to fasten the tubularframe, or reinforcing element, to the body, and adjust it depending onthe wheelbase of the vehicle. These fastening zones are essentially atthe end of the longitudinal tubes 20 and 22.

The reinforcing element 10 also includes side bars 60 and 61, fastenedto the longitudinal tubes 20 and 22, and extending along the side of thebody, to serve as reinforcement in case of side impact. They constituterigid contact surfaces, oriented toward the side to absorb the energy ofa side impact.

The reinforcing element 10 also includes transverse tubes to maintainits various elements relative to one another. There is a rear transversetube 70, connecting the longitudinal tubes to one another at their rearends, at the height of the impactors 30 and 31. There is a fronttransverse tube 72, connecting the longitudinal tubes to one another attheir front ends, and an intermediate transverse tube 71, alsoconnecting the three longitudinal tubes to one another.

Thus, one has an optimized tubular frame, or reinforcing element 10,comparable to a framework, and acting to protect against rear impact andside impact. It reinforces the structure by stiffening it. It is made upof steel tubes or aluminum profiles. The tubes are arranged to make up aprotection structure for a battery or a fuel tank present below thebody, or several batteries and fuel tanks.

The longitudinal tubes 20, 21 and 22 are positioned generally in thedirection of the length of the vehicle, and, with the rigid contactsurface oriented toward the rear made up of the impactors 30 and 31 andthe transverse tube 70 connecting them, due to their mutual arrangement(by welding or any other rigid immobilization means of the tubes withrespect to one another), allow the vehicle to be set in motion in caseof impact at the rear.

It causes the vehicle to be set in motion more quickly in case of rearimpact, owing to its general stiffness and the function contributed bythe impactors 30 and 31, serving, combined with the rear transverse tube70, as pushing device owing to their contact surface, which makes itpossible to prevent too much energy from having to be absorbed in thevehicle. The optimized tubular frame, or reinforcing element,additionally makes it possible to have an energy absorption capacity incase of side impact to protect the members of the battery. Lastly, itadapts to several installations and is adjustable based on the wheelbaseand overhang of the silhouette of the vehicle.

Ultimately, this reinforcing element 10 improves the protection of thevehicle and is adjustable depending on the vehicle. Since it is atubular structure, the steel consumption is kept modest. It is, forexample, possible to save 5 kg of steel relative to a traditional systemcomprising non-tubular reinforcements.

FIG. 2 shows that the structure of FIG. 1 adapts very easily on avehicle comprising, instead of the batteries 2 and 3 (FIG. 1), a battery2 behind the axle 5, and a fuel tank 4 in front of the axle 5. The tank4 is larger than the battery 3, but the reinforcing element 10 issuitable for adapting to its bulk and protecting it.

Owing to this first version of the reinforcing element, the fragilemembers (i.e., the batteries and fuel tank) are protected in case ofrear impact or side post impact.

Optionally, the rear unit of the body can be made lighter with respectto the reference unit from which the model is developed, since thereinforcing element 10 reinforces it.

FIG. 3 shows an alternative reinforcing element, derived from FIG. 1, inwhich the longitudinal tubes 20 and 22 are extended toward the front ofthe vehicle. The tubes 20 and 22 are fastened by fastening zones 110 and111 on the underfloor or bottom of the vehicle, using a system, forexample a screw-nut system. The tubes 20 and 22 are optionally flattenedat the height of the fastener. They are not fastened by the fasteningzones previously described 50 and 51 (FIG. 1).

The front transverse tube 72 is remote from the end of the longitudinaltubes 110 and 111, and near the fuel tank 4, or the intermediatetransverse tube 71.

The reinforcing element 10, in this alternative reinforcing element,includes side absorbers 120 and 121, at the height of the fronttransverse tube 72, fastened to the longitudinal tubes 20 and 22,arranged horizontally and turned toward the outside of the vehicle. Theside bars 60 and 61 are supported by these side absorbers 120 and 121.The side absorbers 120 and 121 make up a deformable energy absorptionzone in case of side post impact at the rear. They protect the battery 2and the tank 4.

FIG. 4 shows another alternative reinforcing element, derived from thatof FIG. 3. In this alternative, the longitudinal tubes 20, 21 and 22 areall elongated, so as to accommodate the presence, in front of the axle5, simultaneously of a battery 3 and a tank 4, making up a larger volumeof members. They are both placed below the body, the tank 4 beingfurther forward than the battery 3. The transverse tube 72 is movedforward, as well as the side absorbers 120 and 121.

It is possible to add side absorbers 220 and 221 in duplicate oppositethe aforementioned absorbers 120 and 121, between the longitudinal tubes20 and 22 and the side bars 60 and 61. This makes it possible to absorbthe energy in the case of violent impact with a side post, for exampleif the vehicle is heavy.

It will be specified that the reinforcing element 10 prevents the rearaxle 5 from experiencing a shock or impact during impacts at the rear,which then makes it possible to use a more cost-effective rear axle,such as an axle with deformable crossmember.

The reinforcing element 10 has a configurable use, since it adapts tobodies including batteries or tanks, in variable number, and it adaptsto bodies with different dimensions (overhang and wheelbase).

1. A reinforcing element for a motor vehicle body, the reinforcingelement comprising protection means for protecting against an impact atthe rear of the vehicle, characterized in that it wherein the protectingmeans comprises at least two tubes to be positioned generally in thelength direction of the vehicle and to be fastened to the body, and arigid contact surface comprising impactors, the rigid contact surfacebeing arranged opposite the two tubes to allow the vehicle to be set inmotion in case of a rear impact, the reinforcing element additionallycomprising energy absorbing means protruding opposite the rigid contactsurface, the energy absorbing means being positioned toward the rear ofthe vehicle, such that the impactors only come into play to set thevehicle in motion if the energy absorbing means have been stressed andovercome by such a rear impact.
 2. The reinforcing element according toclaim 1, wherein the reinforcing element comprises a protectionstructure for a battery or a fuel tank that may be present under thebody of the vehicle.
 3. The reinforcing element according to claim 1,wherein the reinforcing element comprises, for each side of the vehicle,a rigid contact surface oriented toward a side of the vehicle to absorbthe energy from a side impact.
 4. The reinforcing element according toclaim 1, wherein the reinforcing element comprises three tubes to bepositioned generally in the direction of the length of the vehicle, twotubes of which are to be placed between a rear axle assembly of thevehicle and the body, and a third tube, midway between said two tubes,being such that the rear axle is between the body and said third tube.5. The reinforcing element according to claim 1, wherein the reinforcingelement includes at least one fastening means for fastening to theadjustable body to adapt to the wheelbase of the vehicle.
 6. Thereinforcing element according to claim 1, wherein the reinforcingelement comprises, on at least one of the tubes, a means for fasteningthe tube to a bottom of the body.
 7. The reinforcing element accordingto claim 1, wherein the reinforcing element is essentially made up ofsteel or aluminum tubes.
 8. A motor vehicle with a rear axle having adeformable crossmember, wherein the vehicle also comprises a reinforcingelement according to claim
 1. 9. The motor vehicle according to claim 8,wherein the vehicle comprises a first battery beneath the body andbehind the rear axle, and a second battery or a fuel tank beneath thebody and in front of the rear axle, the first battery and respectivelythe second battery or the fuel tank being protected by the reinforcingelement.